In recent years, introduction of a renewable energy power source that uses solar power generated or wind power generated renewable energy is expanding all over the world as a global warming prevention measure.
The solar power generated or wind power generated renewable energy power source does not discharge carbon dioxide caused by combustion of fossil fuel. Meanwhile, power generation output depends on weather conditions such as solar radiation and wind conditions. Therefore, there is a problem in that a mega solar grid connection in which solar power generation panels are aggregated on a large scale or a grid connection of a wind farm in which a number of wind turbine generators are aggregated has a large influence on stable operation of an electric power system.
Therefore, output control capability or connection operation is required to be equivalent to thermal power generation, and for example, the connection requirement of the electric power system of a wind farm is defined in a power company or an international standard. NPL 1 indicates an example of the connection requirement in a power company, and NPL 2 indicates an example of the connection requirement in an international standard.
In addition, in the operation of the electric power system, it is necessary to set a so-called “simultaneous same amount” in which the balance of supply and demand is within the permissible range due to a characteristic in that it is not possible to stably supply power when balance of a supply amount with respect to an amount of demand of power deviates from a permissible range, and it is not possible to store electric energy. The “simultaneous same amount” in the supply of power is legally defined, for example, in Japan, in the Electricity Business Act (NPL 3).
In addition, in the electric power system, maintenance of balance of supply and demand (supply and demand balance) may be broken from a gap (supply shortage caused by power drop, upward swing of demand, and the like) of a power supply plan with respect to prediction of an amount of power demand. When supply and demand balance breaks exceeding a certain range, frequency or voltage of the electric power system varies, an electrical facility of a customer is not normally operated, or the electric power system has even a large power outage in an extreme case, and there is a significant negative influence on maintenance of power quality of the electric power system. In the related art, thermal power generation or hydro power generation is used as a power source for supply and demand balance adjustment to eliminate the influence. Recently, there is a concern that there is shortage of the power source for supply and demand balance adjustment in the electric power system caused by an increase of connection of the renewable energy power source in which output variation depends on weather conditions.
Therefore, a role is desired as a power source with adjustable supply and demand balance of the electric power system in the renewable energy power source itself. For example, PTL 1 discloses a method for driving by intentionally reducing output of each windmill, and securing reserve power in a wind farm.
In addition, for example, PTL 2 discloses a method for increasing and reducing the number of windmill groups for adjusting output variation considering a case in which an incentive is given with respect to output variation reduction of an increase of an electric power purchase price and the like of the wind farm with less output variation when an amount of introduction of the wind farm increases.